Has the prevalence and severity of symptoms of asthma changed among children in New Zealand? ISAAC Phase Three.
OBJECTIVE
To investigate time trends in prevalence of symptoms of asthma by repeating, during 2001-3 (Phase Three), the International Study of Asthma and Allergies in Childhood (ISAAC) Phase One study that was conducted in New Zealand in 1992-3.


METHODS
ISAAC Phase Three involved repeating the cross-sectional questionnaire survey of two age groups of school children (6-7 years and 13-14 years, children and adolescents respectively) using the same methodology as Phase One. In New Zealand it was conducted in Auckland, Bay of Plenty, Christchurch, Nelson, and Wellington.


RESULTS
After 9 years, reported asthma ever increased from 24.6% to 30.2% in children and from 24.1% to 32.4% in adolescents (p<0.001). Current wheeze (written questionnaire) significantly decreased in children from 23.6% to 22.2% (p=0.002) and in adolescents from 29.7% to 26.7% (p=0.047), and for the video questionnaire from 18.1% to 11.1% (p<0.001). There was a significant reduction in wheezing limiting speech from 5.0% to 3.7% in children, and 7.9% to 6.2% in adolescents. Little regional variation was found. A higher proportion of children with asthma symptoms now report having ever had asthma.


CONCLUSIONS
The decrease in prevalence and severity of symptoms of asthma is encouraging, but the reasons for these trends are currently unclear. Increases in asthma labelling are likely to be due to greater awareness of asthma. A trend of decreasing prevalence of asthma symptoms, if maintained, has positive implications for lessened burden of disease among asthmatics and lowered cost of treatment.
Asher
M Innes
MI
Department of Paediatrics: Child and Youth Health, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand. mi.asher@auckland.ac.nz
Stewart
Alistair W
AW
Clayton
Tadd
T
Crane
Julian
J
Ellwood
Philippa Innes
PI
Mackay
Richard
R
Mitchell
Ed
E
Moyes
Chris
C
Pattemore
Philip K
PK
Pearce
Neil
N
D000293:Adolescent; D000367:Age Factors; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D009520:New Zealand / Q000453:epidemiology; D015995:Prevalence; D012135:Respiratory Sounds; D012720:Severity of Illness Index; D012737:Sex Factors; D011795:Surveys and Questionnaires